Memory arrays consist of a number of storage locations or memory cells. Memory arrays are generally coupled to a storage control unit for accessing storage locations (cells) in order to store information in, or to retrieve information from, the memory array. Memory arrays are generally constructed in a reliable and robust manner. However, some random number of memory locations may be or become defective. It is desirable to avoid storing data to, or retrieving data from, defective memory locations. In order to avoid accessing defective memory locations, a memory map is generally devised to map addresses for defective memory array cells to another memory array or another portion of the memory array that is known to be operative. This memory array or portion is commonly referred to as a spare or a redundant memory array. The memory map is stored in another memory array, known as the map memory array. The size required for the spare and map memory arrays depends on the number of defective memory cells to be replaced. If the primary or first memory array requires that all locations be spared, the spare memory array will need to be as large as the first memory array and the map memory array will also need to be large. Since relatively few locations in the first memory array usually are defective, the size of the spare memory array is usually far less than the size of the primary or first memory array. It is desirable, of course, to make the spare and map memory arrays as small as possible, as unused locations dedicated to spare or map memory are wasted and this wastes resources. In order to maximize the efficient use of memory resources, there is need for a method and corresponding apparatus for reducing the amount of data to be stored in the map memory array.